Gas producing and consuming apparatus.



, H. L. DOHERTY. GAS PRoDucING AND coNsUMING APPLICATION FILED APAR. 14

APPARATUS. 1909. nENBwnD H1B. 15, 911.

H. L. DOHERTY.

NG AND CONSUMING APPARATUS.

GAS PRQDUCI APPLICATION FILED APR. 14, 1909. vRIINFWID PEB. 15, 1911.

Patented Apr. 25, 1911'.

3 SHEETS*SHBET 2.

IIIIIIIIII n I I f I I 4 I I I I 5 I I I I I I I I I I l H. L. DOHERTY.

GAS PRODUCING AND CONSUMING APPARATUS.

1L l 0U 1 Kus ..2 n M. d .e 1t In 9e 1 -M un.. Rm E r D E W E N E B 0n 0 9 1 4.: 1 B. E/ A D E L I F N. o I T A o I L P P A 3 SHEETS-SHBBT 3.

uwim/5.9858 FW which the gas from the producer is burned;

. to regulate and cont-rol the. temperature ot' L Y Unir-ED avise, waste'lieat of the products of combusltion themselves.

process.A

'section ofthe 'gas bench onavertical plane .with its connections. Vthrough the left-hand recuperator of the gas Specification of Application nica April vi4, 1909,' serii No. 489,784.l

To a-llvwhom'it may concern: Y

Be it known -that I, HENRY L. Doiinii'iv, a citizen of the United States, residing at New York city, in the countyof New York and State of New York, have invented non' and useful Improvements iii`Gas` Producing andConsuming'.Appiiratiis, of which the following is a specification.

My invention relates to gas producing and consuming apparatus,I and, in particular to apparatuscomprising in combination; a gas producer in which coal or other' fuel is burned iii inost part tocarboii nionoxid, and in which the temperature control thereof is secured by the introduction of regulated amounts of the waste gases troni the combustiono'f the producer gas; a furnace in and air-heating recuperators for heating the air Asnl'ipliedor combustion by the, other- Iii co-pending application, Ser, No. 485887, I have described and claimed, iii apparatus of the kind referred to, the process of regulating the ten'iperature of thev tuell bedof gas producersby introducing thereint'o a currentof mingled air and products of combustion. Y Y' My present invention relates toft'lie appai'atus which furnishes the ineans for the practical utilization of the'above mentioned The objects of my invention .are to conservo as large a proportion possible of the ratus by the waste of combustion, and

the fuel bed in the producer of the appara-V tus more effectively than has heretofore f proven'practicable of attainment in all cases.

. tlic ,accompanying drawings IY have shown an.A apparatus suitable for carrying out my invention."` The particular applicii-4 tion of my,inventionwhichlI have selected' Vfor the purpose of illustration being, that to a combined. gas producer and retort oven, commonly known gasbciicli;' Y

Figure-1',i1s a-view showing al part 'eros-sf through the line A' Av of Fig. y'2., B; 'B'of Fig.l3, and C C of Fig. 5, 'and the `restjin elevation, the latter 4showing the injector, Fig. 2 is a section oAsjPnonuoING AND consumen-rumanos.

, longitudinal section of the etters Iatent.

Renewed February i5, 191i.. Nofeosos'. f-

"Qn 'aieiine of Fig. 1. rig. i is a' pari sor or blower and the 'connections from tlie saine to tlie gas bench.-4 -F1g.55 -is a vertical line F F of Fig. 1.

.bench on the line Dv of 1L'. 3 is a section throuvh the riglitrhand recuperator.

vplan of the apparatusshowing the coinpresgas bench on the I In the several views; 1x is the gas'producer, 2 the retort-oven containing the re 5 and 6' are prelieaters or recuperators located, respectively, on. the right and left sides of the gas producing chamber l.

4 isa'recuperator forming partof' 6 for reheating the products of. combustion on their way t6 the producer.

rlhe recuperatoijl occupies a compartment between the right-hand wall 7 vof the gasprodiicing chamber l'and the right-hand arcliwallSof the gas bench. This compartiiient is divided bystaggered horizontal jartitioiis 9 into'a number.-ofl'horizontal ues, eacli"coniiected at opposite ends Ywith the flues lying nextV above and below. Theresult is that the horizontal tlnes forni together a retui'n-bcnd flue 10. At the outerfendvof the lowest'sectionof 10 is anair damper orV register 11livhichcontrols the .admission of' air thereto.' TheV up erniost sect-ion of 10 communicates thi-OngiA a ort 12wit1i the lower of a setfof two equa izing flues desig- Y nated by 13 `and 14.3l 'Ports 15 establish conimiinication betweenV 13 and 14 at various` points along the length of the saine.` Covering the orificesv or ports 15 are tiles, ,16, which maybe adjusted `by means of "a metal rod or hook'intr'oduc'ed through an appropriate hand-hole in the front of the bench so as'to cover more or'less of the ports 15. By

tioiv of air from 13 and 14 inay be inade uniform along the llength of the flues. Opening out 'of 14 'are a seti of short -fliies 17. -1

These communicate with` cross tlucs'18` and a horizontal fluedlt), running longitudinally of the retoijtiloven..Opening out of port'19 are a" number of ports Vor nostrils 20.I `Lo cated Within and enveloped the/ 1lreturn 'bend flue 10 "is another return-bend 'f liie 21.

The upper sections of 21 are .of ieflay or other refractory .material 'while tlielower Y sections are preferably Vof metal. `In the upper part of the recuperator the temper'iature l, is, approximately; 1600 to '1800? Fab., ivthich' nieans of these tiles it is evident that thel fir-21s,' of course, too for ordinary metal dues ermits of the highest practicable. rate of' 'eat transmission rom the producer gas to .the air. The lowest-section of Hue 21 communicates with a stack flue 22 and another 1ue23 leadingto thjeblower 24. The upper Section of 21 has orifices 25 which establish communication' between the retort-oven 2 and the lue'21'- Part of the products of Vthe combustion of the. )reducer gas generated in the gas producer, .enter the fiue 21 through' the oriiices125, pass'through 21 and through the flue 22 to the stack, or through 23 to the blower. The air Aentering "at 11 passes through the recuperator by means of the flue in a direction parallel but opposite to the current of products of combustion pass- Ing through 21. The result is thatthe air current takes up the heat from the latter and discharges through the air ntytrils 2O into the retort-oven at a temperature approximating the one at which the products of combustion enter the flue 21. Y t

The recuperator G, occupying aconipartnient includedbetween the left-hand wall vof the producer 26, and the left-hand wall 27 of thebeneh, is divided into two distinct recuperators, onen for heating air and one for relvsating products of combustion, vwhich I will designate by 28 and 4, respectively.

.lhc recupcrator 4 occupies a position in the middle of recuperator 28. This is be- "canse the products of combustion which pass through 4 enter at a .tel'nperaturc'approxi- Since, m practice,

Fall. between` the heating vand thc heated medium is desirable I aim to place .the recupcrator 4 in such a position in 28 that the heating current of products of combustion discharging from 4, shall he at .about 700 llah. l n the design of apparatus shown the reheatcr Lis divided .into a. rctuluhend 'flue 2f) by staggered horizontal partitions 30. 22 receives the products of combustion that have passed through the upper part ot'v re- 1 cuperator 28-and discharges them into the lower part of 28. v

-Locat'cd in 29 is a return-bend tlue 31 for the current of products of combustion going Vto the'injector 32. i This flue 31 is madeup ot' a number of horizontal sections, which consist of a number ofvpipcs V(four in thc designv shown) -which enter headers, 33, t

either end. These headers are Valternate y separated and connected soas to form a return-bend flue, 'the horizontal sections of which are composed of'a numberof parallel portion of the passageY 36, which` Visconnectpipes. The 'products of combustion or flue gases ygoin end of 31 rom the pipe 34,which is the disto the injector enter the lower f charge pipe from the blower24, pass'throughV products v(if-"combustion passing type, and in design shown is, essentially Y a 'nozzle-shaped passage 36 having 4an inner nozzle 37 through which the flue gas under pressure 1s' disc iarged into'the convergingthrough'theltwo fines, 38, (one for each air recuperator) withv tl1e.liues'13 und 3S).

ing through 37, in the well known' manner, draws down through 38 a portion 'ofthe heated air from Ythe lines 13 and 39, and forces the'inixture of heated air and flue 'gas into the inelosed ash-pit of the' producer.

The relative proportions of flue gas and air are regulated by means of the valve 42,v the pressure under Awhich the flue gas is'supplied to the injector and by manipulating the dalnpers 43, one on each of the fines 38.

v The current-,of compressed flue gas d ischar, 1;4

The air recuperator 28is divided into a number of horizontal lines by staggered horizontal partitions 44, the partitions being of snella-length as to leave ports 45, through which communication is established between the difl'erentsub-fiues. It."Y is evident 'that' the arrangement furnishes two return-bend flues, 46l and'47, connected by the returnbend flue 29 o'tl reheater 4, so that the three flues, 4G, 29 and 47, form 1n reality ,one continuons flueV through the rccuperators 28 and 4.

The upper end of 46 is connected with the flue 48, the latter having orifices 49 which establish co-n'xmunieation between 48 and thet reYrt-oven. 'lhediseharge end of47 commuulcates with the stack flue 50. A flue 51 pipe 52 of the blower 24. Dampers, .53, 5ft and 55 on 23, 51 and 52, rcspect1vely,scr\'e to regulate the low 4of products ot' combus-I tion through the respective pipes.

Located within the fiues 46 and 47 are rc- I turn-bend flues 56 and 57, respectively,

joined by the connection 58, so as to' form a ing flue 39. Thev system of flues, 39, 40, ($2, 63 andV 64, are exactly similar in construc- Atio-n and function to,thercorrespondinglines,

13, 14, 17, 19 and. 20, 0..-.recuperator-5, and need no further description. The function ofthe cross fines 18 is to equalize the dis- .is connected with 50 and withl the suctionV port 61 establishes` communication between Vthe uppermost section of 46 and .the equal1zv1ero Y .perature .control the volume'o is dilicult Yto introduce suiiicient flue'.

esl

tribution of theair between the two sets 'of air nostrils 20 and 64. `This Across iue 18 -is in the design shown formed by/the hollow arch-keys 65. Between'the keys (l5-are left" the openings or nostri1s6G,fwhicl1 allord'a passage for Ithe producer gas formed' in the producer 1 to the 'combustion' chamber ofthe retort-oven- 2. .v

. The gas passingthrough 66, meeting` the air enterin through-20 nd (34, burns. The

products o the combusti n passup'ward andvr around the retorts 3, and thence through the orifices 25 and 49, andV thence through the combustion gas fines of recuperators 5 and 6 to the stack flues 22 and 50.., From 22 and 50 the products of combustiony pass, in part,

to thev blower 24 and the remainder to thestack.

`The object of passing back to the gas producer a portion of the products of combustion is for the purpose of controlling the described. VIn the operation of this apparaf tus I use 'a jet of compressedflue gast-oinduce a current ofair, whereas in ltheproc-` esses referred to I use a jet of compressed air to induce a currentof products of com- Y bustion. This atordsa more positive .control ovcr the volume of flue gas introduced. Sometimes, where an-excessof-a1r 1s used,

'the prol'zortion of. carbon dioxid'in the flue gas is so small that to secure a roper temi) the latter must be .in excess of th'erformer. lVh'en this-isthe case, unless theairis supplied under 'an -unecon'om-ically vhigh pressure, vit

ucts into the vdraft current. On the other hand, when l'the flue gas is compressed and used fas a jet 'to induce the air current the volume of uc gas in the 'mixture may be increased to any4 Ydesired extent.

The reaction. whereby the temperature control effected is the one fully described in the Letters latent referred to,` viz.,

(l) l CO2+C'=2CO. f VThe j'predominating Produccivreactionv is, L (2') ,C .+O2= 2Co.r

This reaction liberates about 44:50 U.. vper pound of carbon so consumed,'a.nd will,

1f allowed to proceed unmodified, establish a tem rature of about 2700'Fah. in the bed o fuel. This i's far'above the s intering temperature of most fuels, Vand in -order to avoid the annoyances, and loss of economy@ incident'to the 'sintering ofthe ash of the fuel, Iutilze the'reaction (1) to absorb-..5 'as inuclrof lthe excess .heat developed by reaction aswi'll keep the temperature in the fuel bed at between about! 1G00 andf. .-.l -18000 1+i, .-5. Y i f In order to secure the highest economy of af operation it is necessary to provide soinezf-, wayfof retaining in or restoring to the` systemthe` heat carried out of the rctortoven. A by the products -of combustion. Since it is". necessary tomaintain the'walls of 'the 1e-..=',

to'rtsatabout 1900 to 2000o -Fah. in order...

to secure a carboniring temperature in' thecharges' within the" retorts, .it is manifest-...1:1 thatthe products of combustion must beV permitted to 'leave the oven at about thatQj-l Now, the proportion of the total "heat 4developedwhich is contninedin.:

temperature.A

the products 0f combustion at 1800-20009 Fah. isabout 5 5 to 60%. The only way inw;

which this heat canbe recovered and saved .to the, systein is toutilizeit .to prehcat the I air Supplied forthe combustion. But Athe yhea-t capacity. of the air `required for the secondary combustion-is only about (30% ofv4 l" Athe totallrheat'carried by the products ofthe 'combustion vleaving the.1etort n 'en, since it x is, of-r course, practically impossible to heat-A the air above about 1800 I".

Ihave, now, 1n this present. invention, dc-

scribcdand claimed, aineans by which the greater parthof this otherwise unavailalev heat may be saved and utilized.

first thought it mayA seem illogical to: supply additional heat to the gas producer when-I ain purposely introducing.combustion gases containing carbon dioxid to keep down-the temperature therein. As a matter of fact, however, this results in a very decidedl gainin the volume of the chieti combustible constituent of the producer gas, l viz., carbonlnonoxid, that is produced for a"y f 7 11110" given weight ofcarbon consumedinythe producer. The greater the amount of heat that AI can introduce into my producer, the D .greaterns the proportion of carbon dioxid that I can reconvert intothe useful gas-carbon monoxid. Since this Vreaction- (1.) gives" doublet-he volume of carbon monoxid for' a 1 given weight of carbon consumed on the 'f i' grate of the producer, as is give-n by the rc-"f i' action withl the oxygen of theI air (reaction 2) it is plaiu'that-for every B." T; U. ot'-V sensible heat that I supply to the producer heat, which-is returned in an' available forni 4to the'retort'oven. i a The practical h eat' capacity of the'prii`- mary and'secondary air, alone, is 'not suffi-*"3* 'cient to takeup the heat-'carried'out of the j y'i retort-oven bythe products of 'combustio`n,`. I` `and therefore if I- depended upon the air alone .to restore this heat to the system there would still be a. la-refe unavoidable waste. By the means which f have herein described and claimed for taking up part of the sensi# ble heat of the Hue gases in the portion -6 thereof which I use to control the tcm ra- -tu're in the,producer, I have leftl for the air to take up only a quantity of heat fairly commensurate with its practical capacity. p By the process dcscril` d in the Letters PatY '10 `en t, above referred to, the preheavting of the "f primary air is not practicable owing to the act that the volume 'of flue gas which must lthen be introduced is i economically handled By tliem'eans which I have herein described and claimed I have ovei'come the l ditiiculties in the way of a thorough recupery ation of the heat of the waste gases from the retort oven, and increased the etliciency 2,0 of the gas bench to that extent. A I Iaving described my invention, what I l claim is: i

1. In a combined gas producing and gas consuming apparatus, the combination of a 2,5 gas-producer; a furnace for burning produccr gas; recuperators for transferring heat from the products of combustion leaving said furnace to auair current;"nieans forcompressinga kportion of the products of combustion leaving said recuperators;

' means for introducing products of combustion and a portion of such heated air into the said gas producer;

greater than can be by the air jet. 1,5

ofsuch heated air into substantially as described. Y

2.- The combination of a gas producer; a furnace for burning the gas from said pi'oducer; recupe `atoi's for heating air by the 40 products of combustion from said furnace; meansI for compressing' a ortion of the products of combustion at ter they have. passed through said recuperators; means for reheating said compressed products of com- 4g bastion; eans for intrml'uciiig said' reheatted products of combustion together with t a'portion of the said heated air current, into 1 v I said gas producer; and means for introduc-V L 1 ing the remainder of said heated 4air into 4{it} saidfurnace, substantially as described. Y Y 3, Ina combined gas producingr andgas i coi'isuining apparatus, the combination of 'l said furnace, all

recuperators for heating the air supplied toV l, the gas producing apparatus and the air v' .supplied to the gas consuming apparatus in a common current; means for reheating' a part ofthe products of combustion from the gas consuming portion of. the apparatus VI after they have passed through said .re-

i 60 cuperators; and means foriutroducing said` i reheated lproducts of combustionin admix- 5 ture with a port-ion of said current. of heated air into the gas producing portion of said apparatus, substantiallyas described.

t5 4. In a combined gas producing and gas such portion ofthe and means for introducing the remainder .said gas producer;

consuming (apparatus, the combination rzcuperators .for heating the airsu plied to t ie supp ied tothe gas consuming apparatus in part of the products' of combu'stion'from the gas consuming apparatus after. they have passed through said recuperators; an

communicationwith the airtiues of said air recuperatois, its-discliarge end in :communication with the gas producing fportionV of and a nozzle through which the pressed products of combustion are discharged, whereby a portion ofgthe heatedV air is withdrawn froml said .heated air current and mixed with the said compressed products of combustion and the gaseous mixture introduced into the gas producing portion scribed.

5. In a combined' consuming apparatus, the combination of reeuperatoisiforl heating the air sipplied to the gas producing apparatus an a common current; means for compressing the. gas consuming apparatus after the same have passed through said recuperators; a

recuperator for reheatingfsaid compressedf prod nets of combustion; an inductor having its induction" chamber with the air tlues of saidV air Y y its discharge end in communication with the gas bed combustion are'discharge'd whereby a orthe said air recuperators, through saidinductor and mixed with the products of com-v bustion discharging through said nozzleand the gaseous mixture introduced into said bed thereof, substantially as described.

(3. The combinatioirof a. furnace Yfor burning the gas generated in recu perators for heating the' air for lsaid gas producer-and said fur# nace, comprising, passages for air and separate passagcs'for products of combustion air passagcsof said recuperatoi's with said furnace and. passages connecting said air thi` discharge endof said inductor with'the gas producer; means for compressing a'porf tion of the combustion gases recuperators; and a passage'eonnecting said acomnion current; means for compressing aV a part of the productsof combustion from 95 in communication iecuperators,

producing apparatus beneath the lfuel thereof, and a nozzle through which` the, said compressed and heated products ofV tion of the heated airis withdrawn om..

as roducinfra aratus an the air inductor having its induction chamber-iny 85 of the apparatus, substantially as de-` gas producing and 'gas' the .air supplied to the gas consumlng apparatus 1n gas producingr apparatus beneath the fuel:

gas producer; a

from -said furnace; passages connecting the' passages with the induction chamber ofan indiietor; an Inductor; a passage connecting j compressing means with4 the induction nozzle of said indutor, whereby a current of 1 25 y from said fur-A Vnace after they. haveI passed throi'igh said 990,714, p y ,A 5

hea ted air and products of combustion is introduced into said gas producer, substantially as described. i

7. In a gas bench, the combination of a gas producer, a furnace for burning the gas generated in said gasfpioducer; recupera tors for hcatfingith'e'air supplied to said gas'pro'- -ducer and said furnace, each ofsaid recuper- .ators comprising a return-bendS 'flue V'forprodiicts-of combustion and located within saidproducts-of-coinbiistionfHue' a returnbend flue 'for air; two'equalizing fines havv-`ing a plurality of ports a establishingcoinmunicat'ion between tlicm along the' length thereofe danipers onsa'id ports, a port establishing communication betweenfth'e uppermost section of said return-bend flue for air andthe lower' of, said equalizing iues; a

plurality of passages connecting the upper of said equalizing tie-ues .with said furnace; an inductor having its `dif-:charge end in coniinunicatioii with.r` the gas producer below'the fuel bed tlieieof;passages connecting said inductor with the air tlues of said recuperators; and a ,me-dns -for discharging a cur-"1 rent ot products of combustion through the nozzle of said inductor, whereby a portion of the licatedai-r passing through said air flues is diverted to saidiuductor and admixed with the current of products of conibastion passing theret iilougli and the coin-- bined currents of heated air and products of Vcombustion introduced into said gas producer, substantially as described. c

8. l'n a. gas bench thc combination `of a gas producer; a furnace for burning the gas generated in said gas producer; rccnlvieiators for heating the air for said gasproducer and said furnace. in a common current-,each of said iecupcrators coi'nprising a returnbend flue forproclucts of combustiom'and,

located within and envcloped by said 'prod-v` ucts-of-conibustion flue; a return-bend flue for air;,two equalizing fines lia-ving a -plurality 'of portsl establishing communication between said Icqualizii'ig tlues,y dan'ipers ou said ports; a port establishing communication between the uppermost section of said return-bend flue for air andr the lower of said equalizing tiucs; a plurality of passages coniicctii'ig the upper of said cqnalizing-tlues with said' furnace; an indiictor haring its discharge end in c oiiin'iunication with the gas producer beneath-the fuel bed thereof;

passages connecting said inductor with the' air tlues of said recuperators; a Vmeans for compressing a port-ieri of the products of combustion from said furnace after they have passed through said recuperators; a recupcrator, for heating said Vcompressed products of combustion; a passageconnccb" `nozzle of said indnctor,"substantially as described.`

9. In a gas bench the combination of a ing such rccuperator. with the inductiongas producer; 'a furnace for burning the gas generated in said gas producer; recuperatorsl rfor heatingthe air for said gas producer 'section ,in-communication with a chimney liuc; a plurality of passages connecting the upperof said cqualizing lues of each rccuperator withthe combustion chamber of `4 said furnace; aplurality of cross tlues crossconnecting `the said.plurality of passages .of eacli-ijecupcrator; tlues connecting the lowerniost'scction of the products-of-coinbiistion flue 0f eich recuperator with a draft-accelerating means; a ieheater. for reheatinga portion of the products of combustion, said reheate'r comprising a return-bend flue for products' ofy combustion, a port. connecting .the uppermost, section of said return-bend flue for` products ofcombustioii with one of thcfscctions fof the products-of-coinbustion flue of one of 'the air recuperators, and a "port connecting the lowerniost section of said return-bendjlue for pi'oducts-ot-com- Vbustion with another one of the sections of the.produc'ts-of-conibiistion flue of the said air recuperator, a r'cturn-lwnd flue for reheat-ing products ot combustion located rwithin and .enveloped by saidpi'oducts of combustion flue; a. draft accelerating means; an inductor discharging beneath the grate of said gas producer; :irpassage eonnectiiig thc,saidi dra ft-atazelei'a ting means Vwith one extrcniitfy of the Aprodncts-ot-con'ibiistion-reheating tine, of said rehcatcr :For products of combustion, and a passage connecting the other extremity of said products-of-combnstion-relieating flue of said reheatcr with the induction nozzle of said inductor, all substantially as described.

l0. Tn aA gas bench the combinatitm, of a. gas-producer; a furnace jl'orY burning the gas. generated in said gasl producer; re`

cupciators for heating ailv for said-gas producer and said fi'irnace in a common current, each of said recuperators comprising a returnbend flue `for air,- a. damper on the inletend of said air tine, two equaliz-ing tlucs havingr a.l plurality of' ports establishing comnmnication between said flucs, dampers'ou said ports,ia port establishii'ig communication bctweentlic uppermost section of said return-bend Hue for air and the lower of said equalizing iues, a return-bend flue for products of combustion envelopingsaid return-bend flue for airf' nd havin lts uppermost section-in commu ieation wlth the furnace at the part thereof where the' products of combustion aredischargedtherefrom and its lowest section in communication with a imney flue; 'a plurality of passages connecting the upper of'said equa izing luesf of each recuperator with the combustion chamberv of said furnace; a plurality ofcrosslues cross-connectinv the sai plurality of passages of each recuperator; flue's connecting the lowerrnost section of the products-of-combustion flue of each recuperator with a draft-accelerating means; a reheater lor reheating a ortion of the products of combustion,`sai reheater comprisA ing a return-bend flue for products of combustion, a port connecting the uppermost; section of said return-bend products of combustion with' one of the sections of the products-of-combustion flue of one of the air recuperators, and a port conneeting the lowermost section of'said returnbend flue for roductsLof-combu'stion with another one ci) of-combustion fiue of the said'air recuperator, a return-bend flue for reheating prodthe sections of the products- -uctsV of( combustion located within and cn- Y veloped by said productsof-con1bustion flue,

said reheating flue comprising, a plurality of sect-ions, and having' the adJacent sections connected alternately front andrearyeach Yof said sections comprising a plurality of flues connected to headers at each end, the adjacent headers being alternately in communication with and separated from each other, thus establishing communicationV between adjacent sections alternately in front and rear; a draft-accelerating means; an inductor discharging beneath the grate of said gas producer; a passage connecting the said draft accelerating means with one extremf 1ty of the pr0duets-ofcombustion-rcheating Y Hue of said rehea ter for products of combustion, and a passage connecting thc other extremity of said products-of-eombustion-reheating flue of said Yreheatcr with the induction nozzle of said inductor, all substantially as described. Y 1 f Y VSigned at New Y rk city, in the county of New Yorkand State of New York this 10th day of April, 1909. 1

HENRY L. DOHERTY.

Witnesses:

LoUIs F. MUsIL, C. B. Ginnnn'r. 

